Area51 is the evolution of the class game Pong.
You bounce the ball between yourself and the opponent but at the same time you are able to shoot your opponent and the unfortunate baby alien floaters that get in the way.

Evil is stirring in the West. Steambots and bandits have taken over the border towns. The townsfolk have fled telling wild tales of a mysterious steam-powered army bent on destruction and chaos. Yet they cling to hope. For an old Indian legend foretells that when darkness threatens the land...heroes will rise...